In automatic programming for creating NC data using an automatic programming language such as APT (automatically programmed tools) or FAPT,
(a) a part program based on the automatic programming language is created by defining points, straight lines and circular arcs using simple symbols (this is referred to as "figure definition"), and defining a profile using these defined points, straight lines and circular arcs (referred to as "motion statement definition"), and PA1 (b) the part program based on the automatic programming language is subsequently converted into NC data, which comprises NC (numerical control) data (EIA codes or ISO codes) in a format capable of being executed by an NC unit.
In accordance with this profile definition method in an automatic programming system, the conventional practice is to display the figure elements such as the defined straight lines and circles on a display screen, designate the starting point of the profile and then designate the abovementioned figure elements one at a time in order starting from the starting point to define the profile. For example, in a case where a profile OLF [displayed in the form of a bold, solid line in FIG. 12(b)] is defined using already defined straight lines S1-S5 and an already defined circular arc Cl shown in FIG. 12(a), the profile is specified by selecting a starting point Ps using a tablet device, then selecting a figure element portion (a profile constituent element) E1 between the starting point and the next point of intersection P1, and thereafter selecting figure elements in the same manner. GCS is FIG. 12(b) denotes a graphic cursor.
In accordance with this conventional method, all of the defined figure elements must be displayed on the display screen and the profile constituent elements must be selected from these figure elements. In other words, in the prior art, the required profile constituent elements must be selected from all of the figure elements on the display screen while being verified visually. In this conventional method, however, the selectable profile constituent elements are all figure elements. Consequently, when designations are made on the screen, errors sometimes arise owing inadvertent selection of other elements or selection of figure elements which do not intersect with the previously defined figure element. Such selection errors occur with greater frequency the larger the number of defined figure elements.
An object of the present invention is to provide a profile definition method in which the number of selection candidates can be reduced to enable error-free selection of profile constituent elements quickly and easily.